The present invention relates generally to the treatment of hydrocephalus, and more particularly relates to cerebrospinal fluid (“CSF”) shunts.
Hydrocephalus is a condition in which cerebrospinal fluid accumulates in the ventricles of the brain. This accumulation of fluid increases the pressure within the ventricles and without medical intervention can cause brain damage and/or death to the patient. A common treatment for hydrocephalus is to use a fluid shunt system to drain excess CSF from the cerebral ventricles to a second body cavity, typically the peritoneal cavity. By draining the excess fluid, the elevated intracranial pressure is relieved. CSF shunts are well known and used broadly to treat patients with chronic hydrocephalus.
Generally, fluid shunt systems include a valve mechanism for controlling or regulating the flow rate of fluid through the system. Shunt systems typically permit fluid flow only when the fluid pressure reaches a threshold pressure that opens the shunt valve. Fluid flow normally continues until the intracranial pressure has been reduced to a level less than the threshold release pressure of the valve.
Thus, the flow regulating mechanism for most CSF shunts rely on pressure-sensitive valves that open when there is a sufficient pressure difference between the cerebral ventricle and the distal drainage cavity. In theory, this allows the right amount of the CSF to be drained. However, there are a number of problems associated with these shunts, for example, the control of the CSF flow typically is limited to a preset pressure. Although some shunt valves have mechanisms to adjust the pressure difference that triggers the valve to open, such mechanisms are typically cumbersome to use in real situations. In addition, the valves become clogged over time. Moreover, the existing shunts do not take into consideration the effects associated with CSF pulsations. The pressure in the cerebral ventricles will vary, typically in synchrony with the subject's heart rate. Under-drainage or over-drainage may arise due to the mismatched dynamic characteristics of the valve of the shunt and the CSF pulsations.
Accordingly, a need exists for a CSF shunt that can regulate the flow of CSF in a more controlled and intelligent manner. A need also exists for CSF shunts in which the dynamics are sensitive to the fluctuations and flow variation that arise due to CSF fluctuations.